Add in-memory folder hierarchy to probe folder semantics with more
accuracy
PyLong_AsUnsignedLongLong only checks if the number is a long and
will fail if we receive a int. This fix handles both cases
Handle case where open_folder return None
- mapistore_table_get_row is responsible for allocating row_data
- do not Py_DECREF borrowed reference
Add basic debugging to keep track where we are within the test process